1. Field of the Invention
The present invention relates to a combined-type image forming apparatus having a plurality of image forming means according to different image forming methods.
2. Related Background Art
Image forming apparatuses for use in offices, in particular, copying machines, printers, and the like, must have reduced size and high speed operation and be capable of forming an image exhibiting excellent quality. In recent years, an apparatus capable forming a color image has been desired.
Image forming apparatuses usually employ an electrophotographic image forming method or an ink jet image forming method, each of which is a known image forming method. The electrophotographic image forming method is a method in which a toner image is formed on a photosensitive drum by a charging means, an exposing means and a developing means disposed adjacent to the photosensitive drum, and the toner image is transferred to a recording medium (hereinafter called as a "recording member") by a transferring means, and then the transferred image is fixed by a fixing means so that an image exhibiting excellent quality is formed at high speed. The ink jet image forming method is a method in which discharged liquid ink from a recording head is directly allowed to adhere to the surface of the recording medium to form an ink image. The ink jet image forming method is able to reduce the overall size of the apparatus.
To use the advantages of the foregoing two methods, an image forming apparatus comprising both an image forming means in accordance with the electrophotographic image forming method and an image forming means in accordance with the ink jet image forming method has been disclosed. See in particular Japanese Patent Laid-Open No. 4-294379, Japanese Patent Laid-Open No. 5-6127, Japanese Patent Laid-Open No. 5-134824 and so forth. The foregoing image forming apparatuses have the structure with which both methods are used in accordance with the purposes such that white and black images, which are used frequently in an office, are formed by the electrophotographic image forming method and color images, the frequency of use of which is low, are formed by the ink jet image forming method. Thus, an optimum image forming apparatus for the office can be provided. That is, the hybrid image forming apparatus formed by combining the two methods is able to reduce the overall size of the apparatus, form a white and black image exhibiting excellent quality at high speed and form a color image when required.
The present invention is an improvement in the conventional techniques.